How to check if input is a character in python

How to check if input is a character in python

Python program to check if the input is number or letter; In this tutorial, you will learn how to check if the input is a number or letter in python.

  • Python code to check whether a string contains a number or not
  • Python check if given string contains only letter

Python code to check whether a string contains a number or not

  • Take input from the user.
  • Check whether a string contains number or not by using isdigit() function.
  • Print the result.

# python code to check whether a string 
# contains only digits or not 

#
str1 = input("Please enter number or string or both")

# checking & printing messages
if str1.isdigit():
    print("str contains a number")
else:
    print("str does not contain a number")

After executing the program, the output will be:

Execution -1

Please enter number or string or both 1234
str contains a number

Execution -2

Please enter number or string or both test556
str does not contain a number

Python check if given string contains only letter

  • Take input from the user.
  • Check whether a string contains letter or not by using isalpha() function.
  • Print the result.

# python code to check whether a string 
# contains only letter or not 

#
str1 = input("Please enter anything ")

# Code to check
if str1.isalpha(): 
    print("String contains only letters") 
else: 
    print("String doesn't contains only letters") 

After executing the program, the output will be:

Execution – 1

Please enter anything here
String contains only letters

Execution – 2

Please enter anything  hello34
String doesn't contains only letters

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    Python String isalpha() method is used to check whether all characters in the String is an alphabet.

    Python String isalpha() Method Syntax:

    Syntax:  string.isalpha()

    Parameters: isalpha() does not take any parameters

    Returns:

    • True: If all characters in the string are alphabet.
    • False: If the string contains 1 or more non-alphabets.

    Errors and Exceptions:

    1. It contains no arguments, therefore an error occurs if a parameter is passed
    2. Both uppercase and lowercase alphabets return “True”
    3. Space is not considered to be the alphabet, therefore it returns “False”

    Python String isalpha() Method Example:

    Python3

    string = "geeks"

    print(string.isalpha())

    Output:

    True

    Example 1: Working of isalpha()

    Python3

    string = 'Ayush'

    print(string.isalpha())

    string = 'Ayush0212'

    print(string.isalpha())

    string = 'Ayush Saxena'

    print( string.isalpha())

    Output: 

    True
    False
    False

    Example 2: Practical Application

    Given a string in Python, count the number of alphabets in the string and print the alphabets.

    Input : string = 'Ayush Saxena'
    Output : 11
             AyushSaxena
    
    Input : string = 'Ayush0212'
    Output : 5
             Ayush

    Algorithm:

    1. Initialize a new string and variable counter to 0. 
    2. Traverse the given string character by character up to its length, check if the character is an alphabet. 
    3. If it is an alphabet, increment the counter by 1 and add it to a new string, else traverse to the next character. 
    4. Print the value of the counter and the new string.

    Python3

    string='Ayush Saxena'

    count=0

    newstring1 =""

    newstring2 =""

    for a in string:

        if (a.isalpha()) == True:

            count+=1

            newstring1+=a

    print(count)

    print(newstring1)

    string='Ayush0212'

    count=0

    for a in string:

        if (a.isalpha()) == True:

            count+=1

            newstring2+=a

    print(count)

    print(newstring2)

    Output: 

    11
    AyushSaxena
    5
    Ayush

    Time Complexity: O(n)

    Auxiliary Space: O(n)


    How do you check if a character is a number Python?

    Use the isdigit() Method to Check if a Given Character Is a Number in Python. The isdigit() function is used to check whether all the characters in a particular string are digits. It returns a True value if all the characters are digits. Exponents are also confined in the scope of digits.

    How do you check if a input is a word in Python?

    If we want to check whether a given string contains a specified word in it or not, we can use the if/in statement in Python. The if/in statement returns True if the word is present in the string and False if the word is not in the string. The output shows that the word is is present inside the string variable string .